Tuesday, 24 May 2011

Window and roof vents (cutting big holes)

We bought 2 old caravan windows on ebay (about £15 each). One has a hinge, but the other one didn't seem to, so we had to drill holes in the top and fit a hinge.
The first thing we did was try to figure out what size hole to cut. This was not easy! In the end we just sort of guessed and cut a hole in an old bit of plywood. We were wrong, so it was lucky we had practiced first! We tried again and eventually got it right. We also cut out some celotex to line the window to roughly the right depth, then mounted the window to check it would close properly.

Next we cut a big hole in the van!

Then we cut out a bit of celotex to the right shape and glued it in place.

Then we ply lined the top part of the door. This was a bit tricky as the depth of the window was more at the bottom than the top and we had to pad it a bit.
We realised after we did this that a wooden frame would have been better on the inside of the window, for structure and to attach some kind of closing mechanism, so we had to cut out a bit on the celotex and shove some battens in. (When we did the next window we did this properly).

Then we tried to stick the seal on. The seal which came with the window was not wide enough, in fact I don't think you can buy one which is. Also the depth is not the same all the way round, so we ended up cutting in in half. The inside seal sort of stuck, but we screwed it into place as well. The outside seal would not stick, no matter what we used (glue, non-setting mastic, silicone sealant), and also the window wouldn't close because it was so thick. In the end we gave up on the outer seal and stuck draught excluder foam round the outside edge of the window.
To make sure water doesn't get through and run down inside the ply and insulation we used damp proof  membrane overlapping to the outside by about 2cm, which is very sticky and malleable, and hopefully waterproof! I am a bit worried it might melt in intense heat though.
The window now closes and doesn't seem to leak. The closing mechanism (garden wire and screws) is not really pretty, but it works for now.

We did the same for the second window, but it took about half the time because we knew what we were doing! The closing mechanism is different, we screwed 2 L shaped brackets into the sill.

The outside edge needs tidying up!

For the roof vent we got a proper Fiamma 40cm square vent. (about £50).
We cut a 39cm square hole as instructed. We tried to even out the ridges on the roof with some pliers. We made a frame for the inside using 25x 40mm battens (the depth is 40mm, which is the maximum depth the vent can be, and about the minimum the ply lining and insulation can be). We used the sticky damp proof membrane folded up several times, to act as a seal, both on the vent and around the hole. We screwed the vent on to the frame really tight.

It rained yesterday and it leaked a bit! Damn it! There is a slight dent where water is pooling and seeping through. As the roof is so ridged it was pretty difficult to find a place to put the vent where it would be flat. We will have to try to seal it better before we do the plylining.

In the end we bought some Plumbers Mait putty and shoved that in under the gap. We also pushed the van roof up a bit so the water doesn't pool as much. We sealed around the edges with all weather clear tape and this is now waterproof (fingers crossed)!


  1. Get up on the roof with some Silicon sealant and run around the join ... mine were leaking for a while and I did this and they stopped. Loving the blog ... the caravan windows look v professional in the final photos :-)

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